My rack position definitely needs a lot of work, I figure it is because of inflexibility in my wrists and back. My max clean is 255#. Any tips on how I can improve my technique to surpass this sticking point are greatly appreciated!

from that video, it looks like the rack position issue is really more a product of how you're built rather than flexibility. try wider and narrower grips and directing your elbows in more or out more to see if you can find a position that takes some of the pressure off your wrists. remember that your elbows don't necessarily need to be high - the bar just needs to be resting securely on your shoulders.

i would say what's probably holding you back more is your transition between extending up and pulling under the bar - you essentially muscle clean the bar to your shoulders before you even begin squatting under. work on picking up your feet slightly to get them into your squat position and pulling your body down to the bar once you've extended rather than maintaining pressure against the floor and continuing to pull the bar up.